Dendrogram

Definition

A branching, tree-form diagram that visualizes hierarchical relationships among biological entities, most commonly used in phylogenetics to display evolutionary history among taxa or in ecological and genetic analyses to show clustering patterns based on similarity metrics. In entomology and arachnology, dendrograms illustrate phylogenetic hypotheses, population structure, or phenetic groupings derived from morphological, molecular, or behavioral data.

Etymology

From Greek dendron (tree) + gramma (drawing, letter)

Example

A molecular phylogenetic study of wolf spiders (Lycosidae) might present a dendrogram based on COI gene sequences, showing that the genus Hogna forms a monophyletic clade sister to Tigrosa, with branch lengths indicating relative genetic divergence.

Synonyms

• tree diagram
• phylogenetic tree (when depicting evolutionary relationships)

Related Terms

• Cladogram
• phylogram
• phenogram
• consensus tree
• bootstrap value
• hierarchical clustering
• distance matrix
• node
• branch
• root

Usage Notes

While often used interchangeably with 'phylogenetic tree' in casual contexts, dendrogram technically refers to the visual format rather than the evolutionary hypothesis itself. Phenetic dendrograms (based on overall similarity) may differ from cladograms (based on shared derived characters). Branch orientation (rectangular, diagonal, or circular) and scaling (ultrametric vs. additive) affect interpretation but not the fundamental dendrogram structure.